Aye aye, robot: Yanmar develops autonomy for marine engines

While it also has recreational applications, the work recognises a growing need for autonomy in the marine industry, with labour shortages and growing concerns for commercial fisheries workers’ safety driving the research.

“Against this background, maritime robotics technology has made great advances in recent years,” Yanmar said.

“With international manufacturers launching auto-docking and auto-navigation technologies in competition for ever greater precision, robotics has become an established part of the maritime industry.”

Yanmar said automated docking was still presenting the most challenging skill in marine robotics technology – indicating having a human at the controls was still the preferred option.

“The most important factor with auto-docking is improving its level of precision in positioning the boat itself,” Yanmar research and development chief Yuichiro Dake said.

“However, the global navigation satellite system we used for marine navigation was only accurate up to several metres.

“With the preliminary system, real-time kinematic (RKT) was set up port side to send correction signals for accurate positioning.

“We were able to limit precision errors to within several tens of centimetres,” Dake said.

Also helping Yanmar’s marine division was groundwork put in place for the Japanese company’s tractor division, which last year announced it had developed robotic tractors that could drive themselves very precisely.

However, adapting the tractor technology for a boat had its problems.

“A major difference between a tractor and a boat is its condition when it is not in motion,” Yanmar said.

“A tractor will not move from its position once parked. However, a boat will be likely to drift off to its side even when anchored.

“The challenge in controlling the ship was in how to dynamically correct its position.”

To overcome this, Yanmar fitted the system to a ship equipped with twin engines and rudders.

“This configuration allowed control of each propeller, for greater manoeuvrability compared to a single-propeller, single-rudder ship,” Yanmar said.

“The addition of a thruster, a device to enable sideways movement, meant that the ship could move in all directions.

“Yanmar proceeded with the project by concentrating on this type of boat first and succeeded in developing a product within a short timeframe.”

Another big win was that the time needed for the boat to automatically dock fell from four minutes to just 2.5 minutes.

“The preliminary model for auto-docking was too slow,” Naohito Hara, who oversaw the development of navigation systems and control, said.

“A maximum speed in the range of 0.5 to 1.0m/s, meant that while it was safe, the ship ran the risk of becoming an obstacle to other vessels in the harbour.

“We decided to apply an autopilot system that was widely used in the marine industry for automatic steering control so that the two control systems could be used together until docking.”

The latest version of the self-docking boat uses 3D-LIDAR technology to paint a digital map of the boat’s surroundings. The system is so accurate that it can pick out buoys – previously quite difficult for the technology to “see”.

The laser-based 3D mapping system is also used for the automatic navigation system, which uses it to keep the boat well clear of other objects in the water when following a plotted course.

Even so, Yanmar says there is still work to be done.

“All members of the development team agree, Yanmar’s auto-navigation and auto-docking system is currently a step ahead of others in the marine industry,” Yanmar said.

“However, there are still areas of improvement to be considered and further development continues to tackle navigation speed and safety during bad weather.

“The ultimate goal is a completely unmanned vessel with technology which transcends human capabilities and is able to operate as an alternative to difficult and dangerous offshore maritime work.

“Marine technology of the future aims to create a society where people can work and live with peace of mind through maximum work efficiency with minimum manpower.”

The real-world boat is very different to Yanmar's original autonomous boat concept launched in early 2019 – it looked much like a pair of bathtubs bonded together.